Method of and apparatus for making slide-fastener stringers

ABSTRACT

A pair of interleaved synthetic-resin coils are separated upstream of the sewing station of a sewing apparatus, then both coils are sewn to respective support tapes, and finally the two coils, with attached tapes, are interleaved again just downstream of the sewing station. The sewing station can include a pair of plates defining a Y-shaped channel which serves to hold the coils and tapes during sewing and to mesh them together immediately afterwards.

United States Patent [56] References Cited UNITED STATES PATENTS [72] Inventors AlfonsFrohlich;

Karl Rohn, both of Essen, Germany 55 06 2 22 mm mm mmn mm n "n Tm m u S P J P .m r mm a PS w R 004 56 99 w MUM 11 m m 600 E 61 W 78 m 55 h n 23 P G A g 07 79 91M 1 ,0 91 W .i mwm SJJO 0 de N e6 wmfl D... aS AFPA 11]] 253 2247 [rill Burgstn, Glarus, Switzerland Altorney- Karl F. Ross a s dg e am he rs e .m t f f 0 .N am Pa m w Tu Md m mm AS paratus, then both coils are sewn to respective support tapes,

d 6mm VS a 83 nh r-lc mw .mme p ee h f s mn a l t g mm n and finally the two coils, with attached ta again just downstream of the sewin tion can include a pair of plates defi ch serves to hold the coils and ta mesh them together immediately afterwards.

[54] METHOD OF AND APPARATUS FOR MAKING SLIDE-FASTENER STRINGERS 9 Claims, 4 Drawing Figs.

pes during sewing and to mama's mu 1 m:

I SHEEI 1 0F 2 ALF-OMS FROHLICH KARL ROHN ATTGRNEY PATENTED JAM 1 i972 SHEET 2 [IF 2 FIGQZ lOb' ALFONS FFZ'6HLICH KARL ROHN Karl ATTQRNEY METHOD OF AND APPARATUS FOR MAKING SLIDE- FASTENER STRINGERS The present invention relates to a method of manufacturing slide fasteners and an apparatus for carrying out the method. More specifically, this invention concerns slide-fastener stringers having two synthetic-resin monofilament coils each of which is attached to the edge of a textile support tape.

Two methods have been used generally heretofore to manufacture slide-fastener stringers. The first comprises the simple steps of sewing each coil to its respective support tape, and thereafter matching up the stringer half so formed with another stringer half similarly made. Such a method makes it possible to sew at high speed and thereby produce a great number of fasteners in a small amount of time. However, such fasteners often are crooked since the spacing between the teeth of one half differs from that between the teeth of the other half imparting to the finished fastener a tendency to bow.

Another method which avoids this problem of bowing provides for the simultaneous manufacture of both stringer halves by sewing both tapes to two interleaved coil at the same time. This method is advantageous in that it ensures that the spacing remains perfectly the same between adjacent teeth on the coil, and, since synthetic-resin coils are often made by winding two synthetic-resin monofilaments in opposite directions over each other on a mandrel, in that it permits the use of the two coils in the interleaved condition. The disadvantage of such a method, however, is great; the sewing must be done carefully and slowly since the needles must just engage within the exposed bights of each turn without hitting the teeth. Thus, a high-quality fastener is produced, but slowly.

It is therefore, an object of the present invention to provide an improved method of and apparatus for manufacturing slide-fastener stringers.

Another object is to provide such an apparatus and method which overcome the above-given disadvantages while retaining the above-given advantages.

Yet another object is to rovide a method which can be carried out on conventional apparatuses with changes not requiring complete rebuilding of the sewing machines.

The above objects are obtained according to the present invention by an improved method wherein the two coils are fed to the sewing apparatus in an interleaved condition, are separated upstream of the sewing station, and are interleaved together again just downstream of this sewing station, i.e., after being sewn onto respective support tapes.

All of these steps are carried out simultaneously and continuously. In such a manner the spacing between adjacent coil turns is carefully maintained the same since these coils are left interleaved up to the last minute possible before sewing, so that the finished slide-fastener assembly will not buckle or bow. At the same time the full turn is exposed under the sewing needle so that the sewing operation can be carried out at high speed, for large productivity. Immediately after sewing, the two coils are interleaved again to form a finished slidefastener stringer.

The two coils, according to another feature of the present invention, can be separated and then fed through a series of guides which keep the interturn spacing the same by tensioning the two coils to the same extent and/or by making them both travel along paths of identical length.

The above and other objects, features, and advantages will become apparent from the following description, reference being made to the accompanying drawing, in which:

FIG. I is a perspective, partially broken away, and partially diagrammatic view of the apparatus for carrying out the method ofthe present invention;

FIGS. 2 and 3 are views taken along line ll-ll and III-III of FIGS. 1 and 2, respectively; and

FIG. 4 is a view similar to FIG. 3 showing an alternative embodiment ofthe present invention.

There is shown in FIG. I an apparatus having a supply 6 of a pair In of interleaved coils. The pair la is separated by a pin 13a extending across an opening 13c in a member 13b forming a separator 13 that divides the pair 10 into two coils 1. These two coils 1 then pass between a first pair 9 of guide rollers ineluding a driven roller 9a formed with coil-receiving circumferential grooves 9d and an idler roller 9b both mounted on a member 9c pivoted at 9f and urged by a spring 9e in the counterclockwise direction to tension the two coils 1. From the first guide roller arrangement 9 the two coils l extend substantially parallel to each other to a pair of guide eyes 12 mounted on wires 12a fixed to a pivotal shaft 12b coupled to a potentiometer 21. Thence the coils 1 pass over idler rollers 9g formed with grooves 9i and mounted on a fixed plate 9h. A second roller 9g can also be mounted on this plate 911, or three or more can be provided in order to make several stringers 3 simultaneously.

Thereafter the coils pass between a roller assembly 8 comprising a smooth cylindrical idler roller 8a and a longitudinally ridged driven roller 81; formed with circumferential coilreceiving grooves 8c and being supported by its drive shaft 8f on lugs 8d of a fixed support 8e.

A pair of support tapes 2actually two pairs for the apparatus here shownis fed to the roller assembly 8 past a guide 14 which spaces them exactly parallel to each other. Each tape 2 is juxtaposed with one of the coils l and they are all thence fed to a sewing station 10 under a vertically reciprocable block 5 mounted on a rod 5a of a sewing assembly 5b and carrying a needle 4 for each coil 1 and engageable through this coil 1 to fix it to its respective support tape 2.

Downstream of the sewing station 10 is a roller assembly 7 comprising an upper roller 7a mounted on a downwardly biased fork 7b and a lower longitudinally ridged cylindrical driven roller 76 formed with a single circumferential groove 70' adapted to receive the interleaved coils 1. The roller 70 has a drive shaft 7e coupled, along with the shafts of rollers 9a and 8b to a drive motor 22 which is controlled by the potentiometer 21. This motor 22 also is coupled to the sewing drive unit 5b. Thus, as the tension between the rollers 9g and the roller assembly 9 increases, the potentiometer 21 will regulate the motor 22 to decrease the speed of roller assemblies 9 and 7, as well as that of the sewing unit 5b.

FIGS. 2 and 3 show the sewing station 10 in greater detail. It comprises basically a pair of plates 10b and held together by screws 10d. The plate 10b is formed with holes 20 staggered in the transport direction shown by the arrows 23 for passing the needles 4. The plate 10b is formed with a wide shallow groove 15 which is separated into two branches at its upstream portion by a web 18. This groove 15 acts only as a guide for the tapes 2. The plate 10b is further formed with a Y- shaped groove having a pair of anns l6 and a leg 19, the arms 16 being separated by the web 18. The width and depth of the groove l6, 19 are dimensioned to snugly and slidably receive the coils 1 underneath the tapes 2. At the forked region 11 of the plate 10b the two coils 1 are forced together and interleaved, just as is done in a slide-fastener slider, to form a coupled slide-fastener stringer 3 (see FIG. 1). This interleaving region 11 is downstream of the needles 4 so that the coils 1 are sewn to the tapes 2 in the uncoupled condition, but immediately thereafter the two stringer halves l, 2 are interleaved. The plate 10b is also formed with slots 17 allowing throughpassage of the needles 4, which in his case attach the slide-fastener advantageously from the back.

FIG. 4 shows an alternative embodiment wherein a plate 10b is formed with a groove 19' having an island 18' directly between the slots 17 accommodating the needles 4. In this manner the separator 13 can be eliminated and the two coils maintained coupled together-appropriate grooving of all the guide roller-up until immediately before the sewing location since the needles 4 straddle the island 18, and then recoupled immediately afterwards.

We claim:

1. In the manufacture of slide-fasteners wherein a pair of support tapes and a pair of interleaved synthetic-resin coils are continuously supplied to a sewing apparatus and continuously advanced in the apparatus through a sewing station in which each coil is sewn to one of the support tapes, the improvement comprising the steps of:

continuously separating the interleaved coils from each other upstream of said station; and

continuously interleaving the coils together immediately 5 downstream of said station.

2. The method defined in claim 1, further comprising the step of maintaining substantially the same spacing between adjacent turns of each coil between the location at which the coils are separated and the sewing station.

3. The method defined in claim 2 wherein said spacing is maintained by feeding the separated coils through the same distance between the separation location and the sewing station.

4. A method of attaching a pair of synthetic-resin monofilament coils to a pair of support tapes for the manufacture of a slide-fastener, said method comprising the steps of:

S. In an apparatus for the manufacture of slide-fasteners therein a pair of support tapes and a pair of interleaved synthetic-resin coils are supplied to the apparatus and are advanced in the apparatus through a sewing station in which each coil is sewn to one of the support tapes, the improvement comprising;

means upstream of said station for separating the interleaved coils from each other; and

means immediately downstream of said station for interleaving the coils together.

6. The improvement defined in claim 5, further comprising, between said firstand second-mentioned means, guide means for maintaining equal spacing between adjacent turns of each of said coils.

7. The improvement defined in claim 6 wherein said guide means includes withdrawal means for pulling said coils and tapes out of said station, said withdrawal means including a pair of rollers engaging said tapes and said coils, said apparatus including means for synchronously driving both of said pairs of rollers.

8. The improvement defined in claim 6 wherein said guide means includes at least one idler roller, the separated coils passing over and around said idler roller.

9. The improvement defined in claim 5 wherein said apparatus includes a reciprocable element bearing a pair of needles each engageable through one of said coils and one of said tapes. 

1. In the manufacture of slide-fasteners wherein a pair of support tapes and a pair of interleaved synthetic-resin coils are continuously supplied to a sewing apparatus and continuously advanced in the apparatus through a sewing station in which each coil is sewn to one of the support tapes, the improvement comprising the steps of: continuously separating the interleaved coils from each other upstream of said station; and continuously interleaving the coils together immediately downstream of said station.
 2. The method defined in claim 1, further comprising the step of maintaining substantially the same spacing between adjacent turns of each coil between the location at which the coils are separated and the sewing station.
 3. The method defined in claim 2 wherein said spacing is maintained by feeding the separated coils through the same distance between the separation location and the sewing station.
 4. A method of attaching a pair of synthetic-resin monofilament coils to a pair of support tapes for the manufacture of a slide-fastener, said method comprising the steps of: advancing a pair of interleaved coils toward a sewing station; separating the interleaved coils from each other upstream of said station; feeding the separated coils toward said station; juxtaposing a support tape with each of said coils upstream of said station as the coils are fed theretoward; sewing each coil to the edge of its respective tape in said sewing station; and interleaving the coils together immediately downstream of said station.
 5. In an apparatus for the manufacture of slide-fasteners therein a pair of support tapes and a pair of interleaved synthetic-resin coils are supplied to the apparatus and are advanced in the apparatus through a sewing station in which each coil is sewn to one of the support tapes, the improvement comprising; means upstream of said station for separating the interleaved coils from each other; and means immediately downstream of said station for interleaving the coils together.
 6. The improvement defined in claim 5, further comprising, between said first- and second-mentioned means, guide means for maintaining equal spacing between adjacent turns of each of said coils.
 7. The improvement defined in claim 6 wherein said guide means includes withdrawal means for pulling said coils and tapes out of said station, said withdrawal means including a pair of rollers engaging said tapes and said coils, said apparatus including means for synchronously driving both of said pairs of rollers.
 8. The improvement defined in claim 6 wherein said guide means includes at least one idler roller, the separated coils passing over and around said idler roller.
 9. The improvement defined in claim 5 wherein said apparatus includes a reciprocable element bearing a pair of needles each engageable through one of said coils and one of said tapes. 